COVID-19: Why did the UK implement strong measures after finding only two patients with the South African variant?

On Wednesday  (yesterday), United Kingdom Health Minister Matt Hancock announced that two persons in the UK had been diagnosed with the South African variant virus and as a result immediate actions were taken, including strict “quarantine” of anyone who has been in South Africa or even been a “close contact” of someone who has been in South Africa within a fortnight (14 days), as well as restricting travel with South Africa. What possible reasons could justify such strong measures?

First, it is important that these two cases were contacts of a traveler from the Republic of South Africa (RSA), as reported Wednesday by Public Health England.

These initially-recognized two cases being contacts of a traveler means that transmission in the UK has already occurred, and many more will occur unless stopped rapidly. Moreover, earlier examples of transmission within the UK (and other nations e.g., the United States) by this RSA variant likely occurred, but were not recognized.

Second, were either of these two contact patients, or the traveler from South Africa under the age of 30? (Anecdotal reports from RSA state that this variant virus is more likely to infect young people.)

Third, had either of these two contacts, or the infected traveler, been infected previously with SARS-CoV-2 and thus re-infected with a variant virus? The UK health minister also stated yesterday that the virus from these two patients will be analyzed at Porton Down (the Public Health England Laboratories). Most likely, this means that the four issues of concern listed below will be assessed in the UK and (likely already in RSA):

• Any increased growth rate or infectivity in cell cultures?
• Any resistance to antibodies (monoclonals or convalescent serum)?
• Any resistance to vaccines?
• Any recombination between UK and RSA variants to produce a third variant (“offspring” or “progeny” virus)? Such novel variants could have different mutation patterns, especially in the receptor binding domain (RBD) that is crucial to infecting human cells and to the efficacy of antibody treatment and vaccines.

Answers to these questions and concerns will be a key contribution to the world by UK and RSA.